A bold undertaking to store one million metric tonnes (1.1 million short tons) of carbon dioxide in a sandstone reservoir 1.3 miles (2.1 km) below Decatur, Illinois, is well under way. The project began last November, and has so far injected more than 75,000 tons of carbon dioxide, almost one tenth of the target. The University of Illinois, which is leading the Illinois Basin - Decatur Project (IBDP), hopes that the scheme will demonstrate the safety and effectiveness of carbon sequestration, as well as raise public awareness of the process's potential environmental benefits.

What is carbon sequestration, again?

Carbon sequestration is quite simply the physical storage of carbon dioxide having captured it from industrial sources such as carbon fuel power stations or from the atmosphere. By storing carbon dioxide underground that would otherwise be in the atmosphere, atmospheric carbon dioxide levels are reduced, and so is the gas's contribution to the greenhouse effect and global warming.

Modes of carbon sequestration

The IBDP employs geological sequestration, which involves literally injecting compressed carbon dioxide into an underground layer of porous rock. Sandstone is ideal. Conveniently, Illinois has ready access to the Illinois Basin - an 80,000-sq mile (207,000-sq km) Paleozoic layer of sandstone. Above it are several layers of shale, which cap the reservoir to prevent the stored carbon dioxide from escaping.

Map of Illinois showing Decatur near to the center (Image: Shutterstock)

Sandstone sequestration is merely one option for subterranean storage, as carbon dioxide may also be injected into oil and gas reservoirs. Unmineable coal has been proposed as another possible store. The ocean depths have also been mooted as an impermanent store of carbon dioxide, but carbon dioxide reacts with water to create carbonic acid, which, it is suggested, could have a detrimental effect on ocean life.

Atmospheric carbon dioxide can also be reduced by preserving and enhancing natural carbon stores such as peat bogs and forests. By increasing the amount of carbon stored in the biomass at any given time, the amount of carbon dioxide that will eventually make its way back into the atmosphere (via the processes of the carbon cycle) is reduced. Of course, all living things die, so such this approach requires the long-term preservation (or better still, growth) of habitats and biomass.

Has this been attempted before?

The IBDP's one million tonnes of carbon dioxide is, at first glance, made to look rather insignificant when one considers that the United States currently injects between 30 and 50 million tonnes of carbon dioxide every year into oil fields. This isn't an entirely altruistic gesture, since the process aids the recovery of additional oil.

Numerous pilot schemes exist that inject between one and and 50 tonnes (up to 55 tons) of carbon dioxide per day - but only commercial, fossil fuel-oriented schemes inject hundreds or thousands of tonnes in the same timeframe. Salt Creek (USA), In Salah (Algeria), Sleipner (Norway) and Weyburn (Canada) all inject between 3,000 and 6,000 tonnes of carbon dioxide daily, in commercial ventures associated with either oil or gas extraction. It is thought that the additional fuel extracted ends up emitting more carbon dioxide than is captured in the process - better than nothing, perhaps, but hardly a greenhouse effect panacea.

So what makes IBDP special?

What differentiates the IBDP is that it appears to be purely for the benefit of carbon dioxide capture alone. Though it is by no means unique in this regard, it may just be the first pilot scheme on such a grand scale. Similar pilot schemes typically capture carbon dioxide in the tens of thousands of tonnes, so it bears repeating that the Decatur Project seeks to capture one million tonnes of carbon dioxide.

Map of the thickness of the Mt. Simon sandstone in the Illinois Basin (Image: Midwest Geological Sequestration Consortium)

It is also the first "large-scale" sequestration project in the USA to take carbon dioxide from biofuel production (or indeed any man-made source) - in this case ethanol. Over three years the IBDP will capture carbon dioxide from the Archer Daniels Midland ethanol fermentation processing plant in Decatur, and inject it into the ground at a rate of 1,000 tonnes per day - a rate in the same order of magnitude as the fossil fuel projects mentioned above.

The safety of carbon storage

IBDP director Robert Finley is adamant that carbon capture and storage has a vital role to play in managing atmospheric carbon dioxide levels. "If you're going to achieve some of the reductions in emission by 2050 that have been set forth by international agencies, you can't come close to those targets without carbon capture and storage being a part of the process," he said. "For us to perfect this in a site that we believe to be safe and effective is very important. We can create a test case that demonstrates the best practices."

"A site that we believe to be safe" - a curious choice of words? Perhaps not, when you consider that a same issue of water contamination that applies to ocean sequestration could conceivably apply to geological sequestration were carbon dioxide able to leak from its sandstone host into freshwater aquifers.

A 2010 study published in Environmental Science & Technology simulated the slow release of carbon dioxide over a period of more than 300 days, slowly exposing it to water taken directly from a number of USA's aquifers including Illinois' Mahomet Aquifer. The study found that the exposure caused a drop in pH of between one and two units, which in turn increased the erosion of rock in the samples, releasing elements contained therein. In some cases these levels exceeded the maximum levels imposed by the Environmental Protection Agency.

The likelihood of such leaks in real-world geological sequestration is not clear, and safety considerations are among the questions we have posed the University of Illinois (we await answers). That said, investigating the safety of large scale sequestration appears to be part of the IBDP's core purpose, and as such the project is being carefully monitored.

Ears underground

The whole process is monitored using geophysical surveying tools. According to the University of Illinois, the reflections of "energy pulses" sent down into the earth are recorded. "It's essentially like taking a sonogram of the earth," said Illinois State Geological Survey sequestration communications coordinator Sallie Greenberg. "Using geophysical technology allows us to create a time-lapse view of how the carbon dioxide is distributed in the sandstone reservoir." A second verification well on the site is used to monitor pressure and fluid chemistry. It's by tracking pressure levels that any leaks would become evident.

"The research that we're doing is very much on the subsurface geologic environment, to make sure that we can do this safely and effectively, and that we can monitor the CO2," Finley told the LA Times. "So we're using our research dollars to answer these important questions about safety and effectiveness, and we don't have to use our Department of Energy-funded dollars to just try to get our flow of CO2."

On questions of safety it may simply be case of not knowing without trying, and in this respect there's inherent value in the IBDP. Perhaps the larger questions surround carbon sequestration's role in combatting global warming. Will it coexist with other carbon reduction measures, or might it serve as a comfort blanket, inadvertently reinforcing humankind's fossil fuel habit?

James lives in East London where he punctuates endless tea drinking with freelance writing and meteorological angst. Unlocking Every Extend Extra Extreme’s “Master of Extreme” achievement was the fourth proudest moment of his life.

The bad thing about this is that it is just taking the problem away from the current and near future generations and handing them off to some other generations down the line. I read about this in Scientific America and the primary author of the article had the arrogance to say that this system is safe and fail proof due to the depth and the thickness of the bedrock layers. Even if there are never any problems with the man made portion of the system (which after injection of CO2 serve the function of keeping it corked up) the planet itself can do any number of things at any time that can/will render any safeguards ineffective. And to think that even an earthquake or something similar is not enough to open the earth to the depths that utilized is a dilusion. Afterall, all of the continents were once parts of single enormous land masses which were torn apart by the physics involved in making and keeping this planet liveable.

Rt1583

Doing this for the reasons they are I can only see harm coming from this? Let it go in the atmosphere where it belongs!

mrhuckfin

This is seen a temporary action to tackle the trouble! well US has this urgency as history record hurricane and super hot summer hit. The ultra cool winter may on this way.....well still so many people disbelief greenhouse effect, this that, whatever reason! so......HAPPY BURNING HYDROCARBON ......................................................................
It up to your to believe greenhouse effect or theory about change of atmosphere density,layer thickness,ratio change effect, background radiation value and minor pressure increasing affect. It up to the moment all your properties destroy be so call natural disaster, when your pain enough you accept change of belief,........all up to yours! I stay at equator...............................we face sea level rise, the matter can be solve much easier.

Tw Tan

Who is to say that this CO2 won\'t kill some resident bacteria that resides in this bedrock? And how many times do we humans import/export something and then later find out we\'ve created a whole new set of problems far worse than the original. Let\'s just figure out how convert CO2 into something useful instead of spending untold zillions trying to sweep it under the proverbial rug.

Buellrider

Nature has found the way to capture CO2. And it\'s not by pushing it underground. Ever heard of photosynthesis anyone? Like, planting trees and use them as a resource?

Frank191

um, isn\'t this a bit like \'fracking\'? you know, the technique for reaching new supplies of oil that involves injecting water into the ground...the thing they think is responsible for earthquakes in this region already?

on the other hand, wouldn\'t it be grand if we discover that this sequestered CO2 has turned into oil in 100 years :)

Enlightened Wookie

@Buellrider
Growing trees also doesnt sequester all that tremendously useful oxygen, and we could think of all kinds of excellent things to do with a million tonnes of lumber. This scheme just seems like a weird no-benefit project to me.

Bob Ehresman

re; Tw Tan

After all of the fraud, extortion, and other chicanery that has been revealed it is amazing that anyone still believes that AGW is real.

Hopefully they really are putting all the CO2 underground so we can get some of the money back out by running the gas through a compressed air engine generating electricity when this non-sense about CO2 is finally dropped.

Slowburn

Every time I see a rare Global Warming article these days I have to check my cache to see if I am in 2006

Todd Dunning

A waste of time and money..

bgstrong

How many trillions $ for this \"anti natural\" enginiering ?
If you are sure helping Mother Earth by sequeestrating CO2( although a usefull nutriement for plants), at least try to convert it in \"biofuel\" with an eco friendly, robust, efficient and cheap process... preferently !

watersworm

There is significant evidence now which counters the greenhouse gas global warming theory, and yet people continue to profit from the paranoia.

Firstly this sequestration project uses CO2 produced during Ethanol fermentation, and the author refers to this as a fossil fuel project. Wrong - this is a biofuel project, and the CO2 release is a zero-net gain for the atmosphere as it was removed by photosynthesis in the first place.

Secondly, large-scale geo-engineering such as this will have numerous unforeseen environmental consequences such as the poisoning of natural aquifers and inevitable destruction of ecosystems as the ph of the earth is changed by CO2 saturation.

Thirdly, what if the real intention for this CO2 sequestration is really a biogenic engineering project? The hope might be that this CO2 can later be released again as natural gas by fracking.

PeetEngineer

We need to focus on real long term energy sources like solar & eventually fusion. (other sources too) Get cheap abundant energy sources of that nature and we will be able to \"unburn\" all of our fuel and store the carbon away as a solid wherever we want to rather than dealing with CO2 which could always seep back up into the atmosphere.

Rustin Haase

For heaven\'s sake, stop all this nonsense and plant trees. Trees absorb CO2, they are also reservoirs of moisture and this prevents drastic changes in climate due to high heat capacity. Who is financing all this bogus science on such a massive scale. Use solar energy to power desalination plants which bring Water to land and away from the Oceans. At massive scales Watering deserts all over the world, a dent will be made in the rise of sea levels.

Dawar Saify

It might not be like the west coast, but the Midwest does have geological activity. Anyone remember this little tragedy?

We can\'t even get a blow off valve to work well enough to prevent deep water oil spills. What makes us think we can vault a large volume of highly pressurized gas. Let\'s not experiment with peoples\' lives.

ms

Sequestration IS OT THE ANSWER! With all the trouble about oil transportation now, the global warming reality, the present knowledge of alternative energies, etc., burying CO2 does NOT eliminate it! Nor does planting more trees to \"offset\" CO2 production. Once it is released the damage is done. Burying it merely delays damage. We gave to increase DRAMATICALLY investing, R&D and manufacture. Concurrently! Yesterday was already our due date! We all have to do what we can, where we can. Every little bit helps!

Patrick Boucher

This project is in Illinois, so you can bet that it\'s going to net millions for some person or some company who is or was lining the pockets of a politician (or several) somewhere. It\'s motivated by greed and nothing more. It will solve nothing except to take money from some people and put it in the hands of somebody who is already powerful enough to lobby politicians for this purpose. It\'s ridiculous. Mark my words, the deeper they look into this project, the more questions there will be to ask. Several years down the road, some poor schmuck that crosses these powerful people will catch the blame for it and the problems it created will all be pushed under a rug. Carbon sequestration as a whole stinks of a complete scam on the public.

Gene Jordan

What if there\'s some leakage of some sort or some natural calamity like an earthquake? The influx of carbon dioxide would kill all living beings within the perimeter of the affected area, victims that would have otherwise been saved under normal rescue strategy! This carbon sequestration thing is not a good thing!

Ashille Ignoranus

re; ms

The BP spill was the result of a bunch of substandard practices and components.

Slowburn

This isn't about "saving the planet." The planet will survive long after homo sapiens has rendered itself extinct; this is about saving US from OURSELVES, even those who disagree with the purpose and/or methods of reducing greenhouse gases.

William Lanteigne

re; William H Lanteigne

Given that this is going on after AGW has been proven to be a hoax it is not about saving anything.